TT-SX 900x Series High-Voltage Differential Probes User Manual
13
3.2
IEC Measurement Category & Pollution Degree
Definitions
Measurement Category (CAT) - classification of testing and measuring circuits
according to the types of mains circuits to which they are intended to be
connected.
Measurement Category
other than
II, III, or IV: circuits that are not directly
connected to the mains supply.
Measurement Category II (CAT II): test and measuring circuits connected
directly to utilization points (socket outlets and similar prints) of the low-
voltage mains installation.
Measurement Category III (CAT III): test and measuring circuits
connected to the distribution part of a
building’s low-voltage mains
installation.
Measurement Category IV (CAT IV): test and measuring circuits
connected at the source of the
building’s low-voltage mains installation.
Mains Isolated: is for measurements performed on circuits not directly
connected to a mains supply.
Pollution - addition of foreign matter, solid, liquid, or gaseous (ionized gases) that
may produce a reduction of dielectric strength or surface resistivity.
Pollution Degree 2 (P2) - only non-conductive pollution occurs except that
occasionally a temporary conductivity caused by condensation is
expected.
